How is our Gut Microbiome Linked to Weight Gain and Obesity?

The gut is the largest endocrine gland in the body and it has its own nervous system, known as the enteric nervous system, that contains millions of gut bacteria. We have more gut bacteria than cells in our bodies. These gut bacteria are recognised as gut microbiota. They play an important role in the digestion and absorption of nutrients, and they can have an effect on chemical pathways that control blood sugar and insulin levels in our body.

The size and diversity of our gut microbiota can alter as a result of diet and environment including infection, disease and what we eat. Research shows that altered gut microbiota configuration is linked to gastrointestinal tract (GI) disease, obesity and metabolic syndrome. If you are struggling to lose weight despite following a healthy diet, your gut microbiota might be the medical reason you are struggling to lose weight.

Obese and lean people differ in the composition and number of their gut bacteria. Mechanistic studies have demonstrated that microbiota can have an effect on the way we utilize and store energy from the foods we eat. The composition of microbiota can change and it can be influenced by our dietary choices.

If two people consume the same foods, the effects within their bodies will differ depending on the composition of their gut flora. One person might absorb and store more calories, thus gaining weight, while the other might not. Research suggests that some people might have a stronger appetite and urge to eat more food due to alterations and inflammation in their gut flora.

By manipulating the gut microbiota, clinicians can support weight loss, and prevent obesity and its related metabolic complications. We can promote the development of healthy gut bacteria, known as bacteroidates, with the consumption of probiotics and prebiotics.

Further research is required to examine whether such microbial variations are the cause of obesity or a consequence of it. Several studies report correlations between obesity and gut flora composition, but whether these are causal or causative remains controversial.